1. Field of the Invention
The present invention relates to an air conditioner having an oil separator for separating oil from refrigerant downstream of a compressor.
2. Description of the Prior Art
Generally, an air conditioner is an apparatus for maintaining an inside air in an optimum condition. Such air conditioner functions to adjust the inside air to temperature, humidity, and wind current suitable to human activities, and simultaneously to remove foreign matters such as dust entrained in the inside air. Among these functions, the primary one of the air conditioner is to maintain the inside temperature in an optimum condition.
A conventional air conditioner, as shown in FIG. 3, includes a compressor 1, a condenser 2, a capillary tube 3, and an evaporator 4. And the air conditioner adjusts inside temperature by means of refrigerant which is repeatedly circulated through the cycle of compressor 1, condenser 2, capillary tube 3, and the evaporator.
The refrigerant cycle operates roughly as follows.
First, a refrigerant is compressed in compressor 1 to a high temperature and high pressure gaseous phase, and introduced into condenser 2. In condenser 2, the gaseous refrigerant is changed into a normal temperature and high pressure liquefied refrigerant as it is heat exchanged with the periphery atmosphere or cooling water. High pressure liquified refrigerant in condenser 2 now loses its pressure and becomes chilled when it passes through capillary tube 3; the refrigerant becomes a low pressure liquid which is apt to be evaporated. So, when the cold low pressure refrigerant passes through evaporator 4, it is evaporated while absorbing surrounding heat. The evaporated refrigerant, that is, gaseous refrigerant flows into compressor 1, and the whole process is repeated.
For a better understanding, reference numerals 5 and 6 in the drawings respectively indicate a propeller and a blowing fan for expanding heat exchanging efficiency. And reference numeral la indicates an accumulator disposed upstream of the compressor for blocking a flow of refrigerant which is not completely gasified, that is, a refrigerant partly in liquid phase, into compressor 1. Finally, reference numeral 9 indicates a refrigerant conveying pipe for conveying refrigerant into the corresponding devices.
Meanwhile, oil is mixed with the refrigerant for lubricating and cooling compressor 1 in the air conditioner, and thus oil and refrigerant flow together inside compressor 1. Accordingly, some oil is exhausted along with refrigerant during exhaustion of high pressure refrigerant, and continuously circulated through condenser 2, capillary tube 3, and evaporator 4.
As the amount of oil circulated with the refrigerant increases, the amount of refrigerant gets smaller, and the performance of the air conditioner deteriorates. When the exhausted oil is not returned to compressor 1, or when the return time becomes late, a shortage of oil occurs in compressor 1, causing the trouble with the compressor operation.
As a solution, as shown in FIG. 4, an oil separation unit provided between compressor 1 and condenser 2 has been suggested. The oil separation unit separates oil from the exhausted refrigerant and returns it to compressor 1, thereby ensuring that the compressor is always properly lubricated.
However, oil separation unit 7 creates a large amount of flow resistance during the separation process. That is, as shown in FIG. 2, an air conditioner provided with oil separation unit 7 may provide improved performance as compared to a conventional air conditioner which has no oil separation unit, but the provision of an oil separator increases the consumption of electric power and thereby diminishes economic efficiency.